The subject application is directed generally to detection of characteristics in electronically encoded images. The application is particularly applicable to detection of one or more portions of an electronic image wherein an object is backlit.
Early image capturing systems involved shutters, lenses, and photo-sensitive material that was chemically changed when exposed to light. More recently, image capture is done with digital imaging devices, such as digital cameras or scanners. A problem area has existed for all variants of image capturing systems when an object, such as a human or building in a captured image, is subject to backlighting. Backlighting exists when the object is between a light source and the image capturing device, such as a camera. The relative intensity of the backlit area to the lighting of the object can wash out or otherwise obscure the features in the object.
Early attempts at obfuscating the effects of backlighting included repositioning a subject relative to the light and image capturing device, such as a camera. By way of example, a photographer may reorient a person so that the sun is to the photographer's back and the subject is positioned to his front. In other situations, a photographer may use a flash to give better illumination of a subject relative to the backlighting.
It is frequently undesirable or impracticable to reposition a subject to avoid backlighting issues. Detection of a backlighting situation allows for steps to be taken to compensate for the deleterious affects.